The present invention pertains to an integrated circuit of a digital filter forming part of the digital chrominance channel of a color-television set and containing at least one adder, one multiplier, and delay elements each providing a delay equal to one-fourth of the period of the chrominance-subcarrier reference of frequency fc.
Color-television sets of this kind are described in Offenlegungsschrift DE No. 28 54 236 A1. There, the composite color signal is processed by all-digital means: In the direction of signal flow behind the intermediate-frequency stages and the video detector, there is a transition from analog to digital signal processing, i.e., an analog-to-digital converter is provided there.
From the circuit technology of conventional color-television sets with analog processing circuitry it is known, cf. by O. Limann, "Fernsehtechnik ohne Ballast", 12th Edition, Munich, 1978, pages 201 to 206, particularly pages 204/205, that the reduction in the amplitude of the chrominance-subcarrier reference caused by the passband of the intermediate-frequency stages must be compensated for by a corresponding opposite frequency response of the chrominance amplifier, so that a response in the passband for the chrominance signal is obtained which is as flat and symmetrical as possible on both sides of the frequency of the chrominance-subcarrier reference, and whose bandwidth in, e.g., the PAL system is 1.4 MHz.